Association Between the Lateral Wall Thickness of the Maxillary Sinus and the Dental Status: Cone Beam Computed Tomography Evaluation.

HEAD & NECK IMAGING

Iran J Radiol. 2014 January; 11(1): e6675. DOI: 10.5812/iranjradiol.6675

Published online 2014 January 30. Research Article

Association Between the Lateral Wall Thickness of the Maxillary Sinus and
the Dental Status: Cone Beam Computed Tomography Evaluation

Saeedeh Khajehahmadi \ Amin Rahpeyma 2 ' , Seyed Hosein Hoseini Zarch 1

Cental Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran
Oral and Maxillofacial Diseases Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran

'Corresponding author. Amin Rahpeyma, Oral and Maxillofacial Diseases Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran. Tel: +98-
5118829501, +98-5118829500, E-mail: rahpeymaa@mums.ac.ir

Received: June 6, 2012; Revised: 28 Apr 2013; Accepted: July 17, 2013

Background: Assessment of the lateral wall thickness of the maxillary sinus is very important in decision making for many surgical
interventions. The association between the thickness of the lateral wall of the maxillary sinus and the dental status is not well identified.
Objectives: To compare the thickness of the lateral wall of the maxillary sinus in individuals with and without teeth to determine if
extraction of the teeth can lead to a significant reduction in the thickness of the maxillary sinus lateral wall or not.
Patients and Methods: In a retrospective study on fifty patients with an edentulous space, the thickness of the lateral wall of the maxillary
sinus,one centimeter above the sinus floor in the second premolar (P2), first molar (Ml) and second molar (M2) areas was determined by
cone beam computed tomography scans(CBCTs) and a digital ruler in Romexis F software (Planmeca Romexis 2.4.2.R) and it was compared
with values measured in fifty dentated individuals. Three way analysis of variance was applied for comparison after confirmation of the
normal distribution of data.

Results: The mean of the wall thickness in each of these points was lower in patients with edentulous spaces; however it was not significant.
There was no association between gender and the thickness of the lateral wall of the maxillary sinus, but location was associated with
different thicknesses.

Conclusions: The differences in the thickness based on the location and dental status necessitates assessment of the wall thickness of the
maxillary sinus in addition to the current evaluation of bone thickness between the sinus floor and the edentulous crest before maxillary
sinus surgery.

Keywords: Cone-Beam Computed Tomography; Maxillary Sinus; Mouth, Edentulous

1. Background

Assessment of the thickness of the lateral wall of the
maxillary sinus is very important in decision making for
many surgical interventions such as Caldwell-Luc surgery,
Lefort I osteotomy, open sinus lift, facial and jaw bone frac-
ture fixation and mini-screw insertion in orthodontics as
well as the diagnosis of chronic sinusitis (1-5). It is helpful
in Caldwell-Luc surgery for producing a window to access
the sinus cavity, in Lefort I osteotomy for exerting straight
or stepped osteotomy, in internal fixation of maxillary
fractures for selecting the appropriate length of titanium
screws, and in open sinus lift surgery for estimating the ap-
proximate difficulty of the procedure (6). However, in spite
of the importance of this issue, there are very few studies
that have evaluated the anatomic features and more spe-
cifically, the thickness of the lateral wall of the maxillary
sinus. It is assumed that extraction of the teeth might lead
to a decrease in the thickness of the sinus wall.

2. Objectives

We designed a study to compare the thickness of the
lateral wall of the maxillary sinus in individuals with
and without teeth to determine if extraction of the teeth
can lead to a significant reduction in the thickness of the
maxillary sinus lateral wall or not. The number of years
that had passed after teeth extraction was not considered
in this study.

3. Patients and Methods

In this retrospective study, we assessed the thickness
of the lateral wall of the maxillary sinus one centi-
meter above the sinus floor by cone beam computed
tomography scan (CBCT) in fifty patients with eden-
tulous spaces who were candidates for dental im-
plant placement (the edentulous space group) and we
compared the results with CBCTs of fifty maxillofacial

Implication for health policy/practice/research/medical education:

The thickness of the lateral wall of the maxillary sinus is very important in decision making for many surgical interventions. In spite of the importance
of this issue, there are very few studies that have evaluated the anatomic features and more specifically, the thickness of the lateral wall of the maxillary
sinus.

Copyright © 2014, Tehran University of Medical Sciences and Iranian Society of Radiology; Published by Kowsar Corp. This is an open-access article distributed under
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Khajehahmadi S et al.

trauma patients who had no maxillary bone and teeth
problem (the dentate group). This area was chosen be-
cause the majority of surgical procedures that need
bone removal to get access inside the maxillary sinus
or osteotomy cuts and osteosynthesis devices are all
involved with this location. The main inclusion crite-
ria were the tooth absence and presence in the poste-
rior maxilla in the coronal axis of CBCTs in the first and
second groups, respectively. In addition, as the maxil-
lary sinus fully develops in 15 year olds (7) and age may
influence the thickness of the lateral sinus wall; cases
were selected in the group of 40 to 60 year olds to bet-
ter match the cases between the study groups. Fur-
thermore, we tried to match them regarding gender
by selecting 25 males and 25 females in each group (50
patients). Three hundred sites were measured; 150 sites
in the dentate group and 150 in the edentulous group.
In each group, half the measurements were done in
males. In every gender, 25 sites were measured in the
first premolar as well as the first and second molars.
The exclusion criteria were positive history of maxil-
lary fracture, acute or untreated chronic sinusitis or
any other pathological lesion involving the maxillary
sinus, including tumors, cysts, and previous regional
surgery such as Cadwell-Luc. All the CBCTs were made
by Promax 3D (Planmeca Co., Helsinki, Finland) at 0.16
mm pixel resolution, 8 kV, 8 mA and 12 seconds. Using
2-mm-thick reconstruction algorithms, the axial im-
ages were reconstructed into para-axial cross sections.
Then, the thickness of the bone was measured in the
second premolar (P2), first molar (Ml) and second mo-
lar (M2) areas exactly one centimeter above the sinus
floor. For this purpose, we used a digital ruler in Ro-
mexis F software (Planmeca Romexis 2.4.2.R) (Figure 1,
2 and 3). The sensitivity of this measurement was 0.01
mm. For confirmation of the data obtained from mea-
surement by Romexis F software, re-measurement was
performed for 20% of the cases. Intrarater reliability
was high for both measurements of thickness (r=0.93).
Data analysis revealed a normal distribution of the
sample (by kolmogorovsmirnov test); therefore, mul-
tivariate analysis and repeated measures ANOVA were-
usedfor statistical analysis.

4. Results

Multivariate analysis was used for comparison of lat-
eral wall thickness of the maxillary sinus as the effects of
gender and dental status were considered in the analy-
sis. It showed that both of them and their interaction
had no significant effect on the wall thickness (P>0.05)
(Table 1).

For comparison between the three bony locations (sec-
ond premolar, first molar and second molar), repeated
measure ANOVA was used. There were significant dif-
ferences between these three locations. Bonefferoni

correction showed significant differences between all
three pairwise locations (P<0.05). The thickest bone was
thefirst molar region followed by the second premolar
and finally the second molar (Figure 4).

Figure 1. The thickness of the bone was measured in the second premolar
(P2) 1 cm above the sinus floor.

Figure 2. The thickness of the bone was measured in the first molar (Ml)
1 cm above the sinus floor.

2

Iran J Radiol. 2014;ll(l)

Khajehahmadi S et al.

A

%

Ml

M2

dertated

edentulous

Group

Figure 3. The thickness of the bone was measured in the second molar
(M2) 1 cm above the sinus floor.

Figure 4. Mean of the bone thickness in the three locations (second pre-
molar P2, first molar Ml and second molar M2)

Table 1. Mean and Standard Deviation of the Lateral Wall Thickness of the Maxillary Sinus in Three Locations, According to Gender
and Dental Status

Group

Tooth, mean+SD

P2

Ml

M2

Edentulous space

Male

1.47+0.26

2.88+0.56

0.89+0.16

Female

1.47+0.30

2.86+0.58

0.81+0.24

Dentate

Male

1.56+0.31

3.03+0.53

0.90+0.21

Female

1.56+0.30

2.97+0.64

0.87+0.21

P-Value 3

0.953

0.723

0.172

P-Value b

0.136

0.275

0.391

a Genders

b Dental status

5. Discussion

While the anatomy of the maxillary sinus septa is well-
identified (8-10), there are few studies about the topogra-
phy of the lateral wall of the maxillary sinus to help sur-
geons who operate in this area. Arman et al. (11) evaluated
30 dry skulls for the thickness of the anterior wall of the
maxillary sinus and revealed that there is no difference
between the right and left side concerning the thickness
of the wall. Our results showed that among the second
premolar and first and second molar areas, the thickest
wall was observed in the bone above the first molar and
the least thickness was documented in the second molar.
It seems that the increased thickness of the lateral wall
of the maxillary sinus in the bone above the first molar is

secondary to the presence of the buttress of the zygoma.
This structure is a part of the maxillary bone that is at-
tached to the zygomatic bone. One of the practical impli-
cations from the findings of this study is that application
of 2-mm-thickness miniplates and 5-mm-length titanium
screws can safely prevent insertion into the maxillary si-
nus cavity. Furthermore, according to the results of this
study, because the mean thickness of the zygomatic
buttress is 3 mm, using this part as a graft for the eden-
tulous anterior maxillary bone would be insufficient in
conditions that thick graft is needed (3). When there is an
insufficient bone height in the maxillary posterior eden-
tulous region, to insert dental implants with a sufficient
length without perforating the maxillary sinus floor,
open sinus lift surgery is indicated. In open sinus lift sur-

Iran J Radiol. 2014;ll(l)

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Khajehahmadi S et al.

gery, the increased thickness of the maxillary sinus wall
is considered as a difficulty factor (6). Because higher
thickness makes surgery harder and longer, knowing
the thickness of the maxillary sinus wall would help the
surgeon to select locations with a lower thickness to pre-
vent surgical complications such as membrane perfora-
tion (6). In addition, piezosurgery is not recommended
in the thick maxillary sinus wall as it is associated with
an increased length of surgery (12 ). One important point
especially in the Cadwell-Luc and open sinus lift surgery
is that the maxillary sinus wall has a considerable vascu-
lar anastomosis (13) and nutritional canals with 2-3 mm
diameter are observed in 7 percent of the individuals
(14). It is more likely to find wider canals in the thicker
wall (6); therefore, the bony window must be made with
more consideration in thick sinus walls to prevent any
unexpected bleeding during Cadwell-Luc and open si-
nus lift surgery.

The thickness of the maxillary sinushas previously
showed to have association with the difficulty of sinus
surgeries.The differences inthe thickness based on the
location and dental status necessitates CBCT assessment
of the wall thickness of the maxillary sinus in addition
to the current evaluation of the bone thickness between
the sinus floor and the edentulous crest or dental roots
before sinus surgeries.

Acknowledgements

There are no acknowledgments.

Authors' Contribution

All authors have participated equally in this study.

Financial Disclosure

There is no financial disclosure.

Funding/Support

This study (number 900305) was supported by a grant
from the Vice Chancellor of Research of Mashhad Univer-
sity of Medical Sciences.

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